On-floor conduits are used to convey electrical power and communication lines to floor locations that are not within the original architectural and electrical planning of a facility, such as a multi-floor concrete building. Such on-floor conduits are unsightly and may also pose a safety hazard to persons working in such area.
One technique for avoiding the use of on-floor conduits involves the drilling of a hole through the concrete floor at a desired location and the routing of power or communication lines beneath the floor and then up through the hole. Transition apparatus known as “poke-throughs” have been developed for use in such interfloor holes. To protect individuals and property, poke-through devices are subject to electrical and fire safety considerations. Among these are two fire-related requirements. First, the poke-through device cannot function as a chimney or fire-advancing flue in the event of a fire on the lower floor. Second, the poke-through cannot function as a floor-to-floor heat conduction path.
These safety requirements have largely been met through the use of intumescent material. For example, a sheet of intumescent material may be wired in place about a housing. The intumescent material reacts to expand to fill the interfloor hole in the event of fire. Furthermore, thermally insulating materials have been interposed between metallic (and therefore heat conductive) portions of the poke-through devices.